This invention relates to heat pumps, and more particularly to a water to air heat pump system which is automatically thermodynamically balanced to operate at optimum conditions using a variety of water sources, primarily from municipal water mains or privately owned water systems and preferably using treated water effluent such as gray water and reuse water, with the intent of returning used water to the water main or other source with absolutely no contamination or reduction in volume of water with only a slight temperature change.
Although the heat pump principle is not new, extensive use of this energy concept in practical devices has only been recently accomplished. Now that energy conservation is of prime importance, greater use of heat pump systems is being made to save energy and achieve lower initial costs of heating and cooling equipment. Heat pumping in its simplest terms is described as pumping heat from a low energy level to a high energy level and using the resulting heat for space and domestic water heating.
Many forms of heat pump systems have been devised. These systems normally include a refrigerant fluid compressor that is interconnected with two heat exchanger units. The two heat exchanger units are alternatively operated as evaporators or condensers depending upon the positioning of a directional control valve in the interconnecting refrigerant fluid conduit for heating or cooling modes of operation. One heat exchanger unit is associated with heating or cooling apparatus, such as a fan and coil type condenser or evaporator. The other heat exchanger unit is operated to either add heat to the system or remove heat by dissipation.
An efficient mechanism to add or draw heat away from the heat pump system is to transfer heat between the heat exchanger unit of the heat pump system and a circulating loop of a heat transfer fluid, usually water. The question then arises how the change in the temperature of the water used to cool or heat the heat exchanger unit of the heat pump system is accommodated. The heat loss or gain in the water must be compensated for, or the water temperature will increase or decrease, as the case may be, beyond tolerable levels.
In accordance with the present invention, a heat pump system is provided which substantially eliminates the problems heretofore associated with water source heat pump systems, including lack of compensation for temperature variations in the water source. Preferably, the water source is treated water effluent such as gray water and reuse water, which is returned to the municipal or other source from which it came without contamination or reduction in volume.
In accordance with the present invention, a heat pump system is provided having a fluid refrigerant compressor. The heat pump system further includes first and second heat exchanger units. Fluid conduit interconnects the fluid refrigerant compressor and the first and second heat exchanger units in a series relationship.
In accordance with another aspect of the present invention, a heat pump system having two stages of operation for selectively heating and cooling is provided. The system includes a fluid refrigerant compressor having an inlet and an outlet and includes a refrigerant fluid. A first heat exchanger unit is operable as a condenser in the system for heating and as an evaporator in the system for cooling. A second heat exchanger unit includes a water source and is operable as an evaporator in the system for heating and as a condenser in the system for cooling mode. Fluid conduit is provided for interconnecting the fluid refrigerant compressor and the first and second heat exchanger units in a series relationship. The heat pump system further includes a valve interconnected in the fluid conduit intermediate the fluid refrigerant compressor and the first and second heat exchanger units for routing the refrigerant fluid in a first direction in the system heating mode of operation and in a second direction in the system cooling mode of operation through the first and second heat exchanger units in opposite directions.